The invention concerns a cardioversion arrangement having an electrode arrangement for the intracardial discharge of electrical pulses in the atrium of a heart, having an electrode line and in the region of its distal end a plurality of electrodes which are electrically connected by way of the electrode line to an electrical pulse-discharging device such as a defibrillator or a cardioverter or antitachycardia pacer.
Certain cardiac palpitations and arrhythmia phenomena, including in particular ventricular and atrial fibrillation, but possibly also accelerating tachycardia phenomena which have not yet passed into the state of fibrillation are electrotherapeutically treated with good prospects of success by applying short-duration electrical pulses or shocks to the sensitive cardiac tissue.
In that situation, in order to rapidly achieve termination of those life-threatening arrhythmia effects with a high level of certainly, relatively high voltages are conventionally applied and high levels of energy are supplied to the cardiac tissue, which in many cases results in tissue damage and serious stresses such as pain for the patient. In addition, in relation to implantable units, the provision of those high voltages and high energy levels requires expensive apparatus implementation with special structural and insulating elements, in particular powerful batteries and capacitors. Finally, electrode arrangements of large area were and still are used for transmitting the cardioversion energy to the cardiac tissue, and the production and implantation thereof involves a high cost level.
The design of cardioverters or defibrillators (hereinafter jointly referred to by the term xe2x80x9ccardioverterxe2x80x9d) and the associated electrode arrangements has been the subject of a drive for increasing perfection. In that respect, on the one hand numerous technical solutions have been proposed for ascertaining and providing, in the best possible differentiated fashion, the energy and voltage required for cardioversion of the specific cardiac arrhythmia phenomena involved as well as advantageous pulse shapes and sequences and on the other hand various electrode arrangements have been proposed, which were each considered advantageous from given respective points of view. In actual fact substantial practical improvements which have promoted the widespread practical use of implanted cardioverters or defibrillators and combined pacemakers/cardioverters have proven successful.
In the course of that development increasingly refined and powerful endocardiac defibrillation electrode lines have been described, which afford considerable advantages in terms of implantation and in regard to the operative risks, see for example WO/A-94/03233, EP-A 0 602 356 or the present applicants"" prior application DE 196 26 352.2. The endeavours in that respect are inter alia along the lines of applying a cardioversion shock to larger areas of the cardiac tissue by the provision of a plurality of and/or large-area electrodes on an endocardiac line, and thereby approximating the area of action of endocardiac electrode arrangements to that of subcutaneous or epicardiac surface electrodes.
Further recent developments concern the combination of endocardiac electrode lines with subcutaneous or epicardiac surface electrodesxe2x80x94see in that respect inter alia WO-A-92/09329 and EP-A-0 522 693xe2x80x94or also with vessel-type electrodes, see EP-A-0 601 383.
EP-A-0 281 219 proposes the use of biphase pulses (which occur in succession in respect of time) of exponentially falling amplitude for a defibrillator. That arrangement has three ring or tip electrodes arranged on an endocardial electrode line, and a subcutaneous plate electrode, and the shock energy is coupled out by way of two outputs which are connected in various alternative forms to the electrodes. Use of the biphase pulses made it possible to achieve a reduction in the mean energy requirement for defibrillation.
EP-A-0 648 514 describes a defibrillation with a pulse generator for multi-phase shock pulses. EP-A-0 574 609 and EP-A-0 646 391 describe uses, which are refined from the point of view of improved current distribution in the heart tissue, of the principle of biphase pulses for a defibrillator having a plurality of outputs for a multiplicity of electrodes, in which the arrangement provides for timed discharge of pulses of different polarities to various electrodes.
The above-mentioned cardioversion arrangements and the other known cardioversion arrangements suffer from various disadvantages. In particular in many cases they still do not allow for reliable defibrillation which affords the patient careful treatment.
The object of the present invention is therefore that of providing a cardioversion arrangement which permits reliable defibrillation which treats the patient carefully.
In accordance with the invention that object is attained with a cardioversion arrangement of the kind set forth in the opening part of this specification, in which the electrode-bearing region at the distal end of the electrode line is split into two branches of which one is in the form of a septal branch and the other is in the form of a lateral branch for assuming a septal position and a lateral position in the atrium or the ventricle of a heart, wherein the branches are respectively provided with electrodes in such a way that each electrode of a branch is associated in pair-wise manner with an electrode of the other branch, for the discharge of bipolar pulses, and the cardioversion arrangement is designed to record intra-atrial electrograms by means of the electrodes by receiving electrical signals between each two of the electrodes in a bipolar mode of operation.
The bipolar discharge of stimulation pulses by way of a plurality of electrodes which are associated with each other in pairs in the atrium or the ventricle of a heart permits, by dividing the defibrillating or cardioverting energy in successive slides, substantially pain-free defibrillation. Insofar as the electrodes are also in the form of sensors for receiving electrical signals, the conditions of the heart can be recorded in a highly differentiated manner and the discharge of current pulses by way of the electrodes can be suitably accurately controlled.
The electrodes are preferably respectively equidistantly arranged on each of the two branches of the electrode line. Together with the paired association of the electrodes with each other, with an electrode line of that kind, the atrium or the ventricle of a heart can be surveyed or measured by virtue of recording electrical signals or stimulated by virtue of the discharge of electrical pulses, in a practically slice-like fashion. Those slices are determined by the electrodes which are associated with each other in pairs and for example can be arranged substantially parallel to each other in succession at a spacing of a centimetre.
A preferred cardioversion arrangement is one having an additional neutral electrode like the housing of an implantable defibrillator, wherein the cardioversion arrangement is designed to record intra-atrial electrograms by means of the electrodes by receiving electrical end signals between the neutral electrode and one respective electrode in the unipolar mode of operation. Such an arrangement increases the number of detectable parameters so that electrotherapy can be still more specifically matched to the symptoms or syndrome.
Cardioversion arrangements are also preferred, which are designed either alternatively or in combination for the discharge of an electrical pulse by way of the neutral electrode and one of the electrodes in the unipolar mode of operation or by way of second electrodes in the bipolar mode of operation. Cardioversion arrangements of that kind make it possible to generate greatly differentiated stimulation patterns which in addition can be very accurately matched to the symptoms or syndrome so that a therapy of fibrillations can be initiated at a very early stage and effected at the same time in a highly efficient manner while dealing gently with the patient.
In addition a cardioversion arrangement preferably has means for the discharge of stimulation pulses by way of the electrodes in the bipolar and/or unipolar mode of operation and means for subsequently recording intra-atrial electrograms by means of electrodes for receiving electrical signals between the neutral electrode and a respective one of the electrodes in the unipolar mode of operation and/or between two of the electrodes in the bipolar mode of operation. A cardioversion arrangement of that kind permits specific stimulation of the heart tissue before recording the electrograms already referred above, for determining the symptoms or syndrome. The latter can be ascertained thereby in a still more differentiated manner.
Also preferred is a cardioversion arrangement having a neutral electrode and control means which are of such a nature that at least two respective electrodes which are associated with each other in paired relationship, of the lateral and the septal branches, are actuable simultaneously for recording electrical signals between the neutral electrode and the electrodes in the unipolar mode of operation, and analysis and comparison means which are such that the electrical signals ascertained by means of an electrode in the lateral branch and an electrode in the septal branch are comparable in terms of their relative phase position or isochronicity. Further preferred embodiments of the comparison means are distinguished in that the electrical signals ascertained by means of an electrode in the lateral branch and an electrode in the septal branch are comparable in respect of their duration and/or their regularity and/or their isoelectric time duration and/or their voltage rise or fall and/or their morphology. The various alternative embodiments of the comparison means referred to permit greatly differentiated determination of the symptoms or syndrome.
Correspondingly a cardioversion arrangement which is preferred is one in which the control means are such that each of the electrodes is actuable with the electrode associated therewith in paired relationship of the other branch, in bipolar relationship, for recording electrical signals between those electrodes, while the comparison means are such that the electrical signals ascertained simultaneously by means of the pairs of mutually associated electrodes are comparable in respect of their relative phase position or isochronicity. Alternatively or in addition comparison means can be such that the electrical signals ascertained simultaneously by means of the pairs of mutually associated electrodes are comparable in respect of their duration and/on their regularity and/or their isoelectric time duration and/or their voltage rise or fall and/or in respect of their morphology.
The recordal of electrical signals both in the unipolar mode of operation between an electrode and a neutral electrode or a bipolar mode of operation between two electrodes and analysis of the signals in respect of the described parameters results in a large number of items of information which can be used to control defibrillation pulses which are possibly required.
For effectively controlling the defibrillation pulses the cardioversion arrangement preferably has a comparative pattern storage means which is connected to the analysis and comparison means and which can store comparative values for the values generated by the analysis and comparison means.
A further preferred cardioversion arrangement is distinguished by control means which are connected to the electrodes of the septal and lateral branches and which are such that the electrodes of the septal and lateral branches are actuable for discharge of a defibrillation pulse in a bipolar mode of operation. In that connection, the pulse control means are additionally preferably connected to the comparative pattern storage means and the analysis and comparison means. Particularly preferred is a cardioversion arrangement whose pulse control means are such that the electrodes of the septal branch can be actuated more strongly than the electrodes of the lateral branch or conversely.
Preferably, the pulse control means are adapted for simultaneous actuation of the electrodes of the septal and the lateral branches and the neutral electrode. Also preferred is a cardioversion arrangement which has an electrode line, which is adapted to assume a position in the ventricle, with ventricle electrodes, and the pulse control means of which are adapted for the simultaneous actuation of the electrodes of the septal and lateral branches and the ventricle electrode. In addition, the pulse control means are preferably of such a nature that the electrodes of septal and lateral branches are simultaneously actuable for the discharge of a defibrillation pulse in the bipolar mode of operation. In an alternative preferred embodiment, the pulse control means are such that the pairs of mutually associated electrodes of the septal and lateral branches are actuable successively for the discharge of a defibrillation pulse in the bipolar mode of operation. By means of the last-mentioned alternative configuration, it is particularly possible for the slices or layers defined by the electrodes of the lateral and the septal branches in the atrium of a heart to be stimulated in succession. That permits particularly effective and pain-free defibrillation.